[2120] | 1 | /* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */ |
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| 2 | /* |
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| 3 | * Copyright (C) 2011, Purdue Research Foundation |
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| 4 | * |
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| 5 | * Author: ? |
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| 6 | */ |
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| 7 | |
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| 8 | #include <cstdio> |
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| 9 | #include <cstdlib> |
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| 10 | #include <cstring> |
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| 11 | #include <cerrno> |
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| 12 | #include <sys/uio.h> |
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| 13 | |
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| 14 | #include "PPMWriter.h" |
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| 15 | #include "Trace.h" |
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| 16 | |
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| 17 | using namespace Rappture::VtkVis; |
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| 18 | |
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| 19 | /** |
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| 20 | * \brief Writes image data as PPM binary data to the client. |
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| 21 | * |
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| 22 | * The PPM binary format is very simple. |
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| 23 | * |
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| 24 | * P6 w h 255\n |
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| 25 | * 3-byte RGB pixel data. |
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| 26 | * |
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| 27 | * The client (using the TkImg library) will do less work to unpack this |
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| 28 | * format, as opposed to BMP or PNG. |
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| 29 | * |
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| 30 | * Note that currently the image data has bottom to top scanlines. This |
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| 31 | * routine could be made even simpler (faster) if the image data had top |
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| 32 | * to bottom scanlines. |
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[2302] | 33 | * |
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| 34 | * \param[in] fd File descriptor that will be written to |
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| 35 | * \param[in] cmdName Command name to send (byte length will be appended) |
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| 36 | * \param[in] data Image data |
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| 37 | * \param[in] width Width of image in pixels |
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| 38 | * \param[in] height Height of image in pixels |
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[2120] | 39 | */ |
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| 40 | void |
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| 41 | Rappture::VtkVis::writePPM(int fd, const char *cmdName, const unsigned char *data, |
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| 42 | int width, int height) |
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| 43 | { |
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| 44 | #define PPM_MAXVAL 255 |
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| 45 | char header[200]; |
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| 46 | |
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| 47 | TRACE("Entering (%dx%d)\n", width, height); |
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| 48 | // Generate the PPM binary file header |
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| 49 | snprintf(header, sizeof(header), "P6 %d %d %d\n", width, height, PPM_MAXVAL); |
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| 50 | |
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| 51 | size_t headerLength = strlen(header); |
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| 52 | size_t dataLength = width * height * 3; |
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| 53 | |
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| 54 | char command[200]; |
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| 55 | snprintf(command, sizeof(command), "%s %lu\n", cmdName, |
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| 56 | (unsigned long)headerLength + dataLength); |
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| 57 | |
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| 58 | size_t nRecs = height + 2; |
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| 59 | |
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| 60 | struct iovec *iov; |
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| 61 | iov = (struct iovec *)malloc(sizeof(struct iovec) * nRecs); |
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| 62 | |
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| 63 | // Write the command, then the image header and data. |
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| 64 | // Command |
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| 65 | iov[0].iov_base = command; |
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| 66 | iov[0].iov_len = strlen(command); |
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| 67 | // Header of image data |
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| 68 | iov[1].iov_base = header; |
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| 69 | iov[1].iov_len = headerLength; |
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| 70 | |
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| 71 | // Image data |
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| 72 | size_t bytesPerRow = width * 3; |
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| 73 | int y; |
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| 74 | unsigned char *srcRowPtr = const_cast<unsigned char *>(data); |
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| 75 | for (y = height + 1; y >= 2; y--) { |
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| 76 | iov[y].iov_base = srcRowPtr; |
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| 77 | iov[y].iov_len = bytesPerRow; |
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| 78 | srcRowPtr += bytesPerRow; |
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| 79 | } |
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| 80 | if (writev(fd, iov, nRecs) < 0) { |
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| 81 | ERROR("write failed: %s\n", strerror(errno)); |
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| 82 | } |
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| 83 | free(iov); |
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| 84 | |
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| 85 | TRACE("Leaving (%dx%d)\n", width, height); |
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| 86 | } |
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